The present invention relates generally to packages and connections adapted for use with high frequency signals and devices, and more particularly to semiconductor device packages having coaxial inputs.
Digital transmission systems and semiconductor circuits increasingly transmit, receive, and process information at high data rates. Increased data rate of signal transmission allows for increased transfer of information over a set period of time. Increased speed of operation of processing circuitry allows for increased processing of transmitted information over a set period of time. Both increased data rate and increased speed of operation of processing circuitry often means that signals propagated to the circuitry or within the circuitry are somewhat high frequency signals.
Unfortunately, high frequency signals tend to radiate energy as they propagate, and tend to do so in a number of directions. In other words, high frequency signals tend to have a number of propagation modes, many of which are not necessarily down a conductive wire path or signal trace forming a signal pathway or data transmission line.
The radiated energy and the number of propagation modes presents several problems. Energy radiated outside the data transmission line reduces the energy available for propagating signals down the data transmission line. The radiated energy therefore results in signal attenuation. Energy radiated from one data transmission line may also interfere with signals propagating on nearby data transmission lines, resulting in crosstalk. Thus, both signal attenuation and crosstalk may result in signal degradation. Moreover, one solution to unacceptable signal attenuation is to increase signal strength, which in turn results in increased energy radiation and increased crosstalk.
Signal attenuation and crosstalk may occur at many locations. One area of concern is the connection between relatively lengthy data transmission lines and semiconductor circuit devices receiving or transmitting signals over the data transmission lines. Lengthy data transmission lines may be designed and constructed to minimize errant energy radiation. Similarly, within an actual semiconductor device steps may be taken, such as providing multiple metallization layers and appropriately routing signals, to reduce the effects of radiated energy on operation of the semiconductor device itself. Transition of signals between a lengthy data transmission line and the semiconductor device, usually through walls of a package containing the semiconductor device, is problematic, as is ensuring that radiated energy within the package does not have negative effects outside of the package.
The present invention therefore provides a semiconductor device package adapted for use with high frequency signals and/or coaxial connections. In one embodiment, the present invention comprises a leadframe including an aperture that is adapted to pass a signal on a coaxial transmission medium through the leadframe. A die is operatively disposed on the leadframe to receive a semiconductor device and a signal path is located between the aperture and the die. The leadframe also contains a plurality of vias to provide an electromagnetic shielding for signals that are passed through the aperture.
These and other aspects of the present invention will be more fully appreciated when the following drawings are viewed in conjunction with the following detailed description.